After spending a handful of years as a development driver for the team, Norris was promoted to a full-time seat for the 2019 campaign alongside Carlos Sainz.
The season proved to be a successful one for McLaren, who closed out 2018 as one of the slowest teams on the grid.
It ended the 2019 standings in fourth, taking its best finishing position since 2012, and scoring its first podium since the opening race of the turbo-hybrid era in 2014.
Norris just failed to end the 2019 campaign inside the top ten, missing out by four points, while teammate Sainz was sixth in the championship.
The Briton won the intra-team qualifying battle at the Woking-based squad, beating Sainz 11-10 across the season. Seidl says that from the first qualifying session in Melbourne last March, Norris instantly proved he was capable of performing.
"Being a rookie and to have such a [good] rookie season is impressive," Seidl stated. "When you go into your first F1 race and go straight to Q3 ith a car that was not necessarily good enough for Q3, confirmed straight out of the box how great of a talent he is.
"He has confirmed that several times during the course of the season, in qualifying but also in the races."
Seidl noticed that Norris approached race cautiously in the opening stages of the season, before becoming more aggressive once he gained experience.
"It was great to see how he was approaching his rookie season," Seidl said. "He took it a bit more careful at the beginning of the season, when it came down to race starts for example, to make sure he finished the race and gained the experience.
"The second half of the season, he got more aggressive at the race starts so I would say he had a sensational rookie season, and we're looking forward to many more rookie seasons with him."